AMERICAN HYMENOPTERA. 217 



Synopsis of the MTJTILLIDffi of North America. 

 BY CHAS. A. BLAKE. 



The object of the present paper is to bring together as far as possi- 

 ble, all the known species belonging to the family ^lutillidfe found in 

 North America, with descriptions also of such as appear to have been 

 hitherto undescribed. 



The species, of which this family is composed, are, unlike the For- 

 micidae or social ants, solitary in their habits, and are generally found 

 in hot, sandy situations. They consist of two sexes — male and female. 

 The males have distinct, more or less prominent ocelli, are winged 

 and occasionally frequent flowers; while the females are destitute of 

 wings and in some genera of ocelli, and are armed with a powerful 

 sting ; the legs are very robust and fitted for burrowing, the tibiae be- 

 ing more or less spinose and the tarsi ciliated; they are found on the 

 ground and run with great rapidity. 



The genus Mutilla is probably the most extensive of any in the 

 Aculcata, and are cosmopolitan in their habitat, being found in all 

 countries, from the torrid to the frigid zones. The species present 

 remarkable differences in the form of antennae, eyes, head, thorax, 

 neuration, and first segment of abdomen, which conveniently form 

 types for sub-generic divisions. In the female the head is transverse, 

 ovate or quadrate, sometimes enormously developed and armed beneath 

 with two or more formidable spines ; the ocelli always wanting ; the eyes 

 ovate, or more generally small, round, and most frequently apparently- 

 simple, exhibiting no traces of reticulation, even under a powerful Icn.-; 

 the thorax is undivided, varied in shape and sometimes more or less 

 tuberculate or sinuate laterally ; the abdomen varies in form, especially 

 that of the first segment. In the male the head is rarely quadrate, be- 

 ing generally transversely ovate; in a few species (those belonging to 

 the subgenus 3Iutilki) the eyes are ovate and more or less acutely em- 

 arginatc within ; the divisions of the thorax are generally well defined, 

 while the neuration of anterior wings varies considerably, especially 

 the form of the marginal and submarginal cells. In the subgenus 

 Sphserop/ha/ma (tho.se having small round, convex eyes) the majority 

 of the species are densely clothed with long or short pubescence, mere 

 or less varied in color, the ornamentation of some being very brilliant 

 and beautiful. 



